Device for filtering rotation and transmission vibrations for motor vehicle comprising same

ABSTRACT

The invention concerns a filtering device for filtering vibrations transmitted by a rotating engine component ( 11 ) adapted to drive in rotation an output shaft ( 19 ), which device comprises a drive shaft damper ( 20 ) tuned at a frequency substantially locked within a range of frequencies to be damped: electromagnetic modulating means ( 23 ) are designed to adapt the frequency of the damper ( 20 ) to the frequency of the vibrations transmitted by the rotary component ( 11 ). The invention also concerns a transmission for motor vehicle comprising a drive shaft ( 11 ), linked to a rotary component formed by the motor vehicle engine crankshaft, an output shaft ( 19 ) linked to the drive shaft releasable via a clutch, a gearbox ( 50 ), said output shaft ( 19 ) being the input shaft of the gearbox ( 50 ), a filtering device of the inventive type being provided for filtering vibrations emitted, hence transmitted, by the rotary component.

[0001] The present invention relates to a device for filtering outrotational vibrations, for filtering out vibrations transmitted by arotary power component adapted to drive an output shaft in rotation; thesaid rotary power component is for example the crankshaft of a motorvehicle heat engine.

[0002] Devices are known for filtering out rotational vibrations, thatconsist of a mass which is elastically coupled on the shaft: suchdevices, known as passive dampers, work very well in filtering outvibrations tuned to a single frequency which is clearly determined, butfor neighbouring frequencies, the vibrations are, by contrast,amplified.

[0003] So-called active drive shaft dampers have been proposed, as forexample in the document FR-A-2 658 888, the construction of which issimilar to that of an electric motor; it is so controlled that thetorque which it supplies works in opposition to the vibration to befiltered out, over a given range of rotation: the electrical powerconsumption of such devices is not insignificant.

[0004] An object of the invention is to overcome these drawbacks.

[0005] According to the invention, a filtering device for filtering outvibrations transmitted by a rotating power component adapted to drive inrotation an output shaft, which device comprises a drive shaft dampertuned to a frequency which is substantially inside the range offrequencies to be damped out, is characterised by the fact thatmodulating means of the electromagnetic type are provided for thepurpose of matching the frequency of the damper to the frequency of thevibrations transmitted by the rotating component.

[0006] Preferably, the damper comprises a rotor consisting of a masswhich is mounted elastically on the output shaft and associated with astator, the modulating means comprising electromagnetic means carried bythe rotor and the stator.

[0007] Preferably, the electromagnetic means comprise magnets defining asuccession of poles carried by the rotor and coils carried by the statorand defining a succession of poles disposed in line with the magnets.

[0008] Advantageously, the coils are disposed axially in line with themagnets.

[0009] In another version, the coils are disposed radially in line withthe magnets.

[0010] Preferably, the rotor is in the form of a disc or isfrusto-conical or cylindrical.

[0011] Advantageously, the magnets are held in position radially by acounter-centrifugal radial retaining hoop.

[0012] Preferably, the filtering device includes a vibration sensoradapted to measure the amplitude of the vibration to be damped out.

[0013] Advantageously, means are provided for supplying current to thecoils of the electromagnetic means, the said supply being responsive tothe result of the measurement of amplitude performed by the vibrationsensor, whereby to create in the damper a torque equal and opposite tothat created by the said amplitude.

[0014] Advantageously, the device comprises a main vibration damperdisposed on the output shaft upstream of the damper.

[0015] The present invention also provides a transmission for a motorvehicle of the type comprising a drive shaft, coupled to a rotarycomponent consisting of the crankshaft of the engine of the motorvehicle, an output shaft coupled to the drive shaft releasably through aclutch, a gearbox, the said output shaft being the input shaft of thegearbox, a filtering device being provided for filtering out vibrationsemitted, and therefore transmitted, by the rotary component, thefiltering device being as described above.

[0016] Advantageously, the clutch comprises a reaction plate, which iscoupled directly or otherwise to the rotary component, a pressure platewhich is coupled in rotation to the reaction plate but displaceableaxially with respect thereto, the two plate, namely the reaction plateand pressure plate, being adapted to clamp between them, under theaction of axially acting resilient means, friction liners carried by afriction disc at its outer periphery, the said friction disc having ahub which is mounted in rotation on the output shaft.

[0017] Preferably, the friction disc comprises a torsion damper whichconstitutes the main damper.

[0018] In another version, the reaction plate constitutes the secondarypart of a two-part flywheel, the other part of which, namely the primarypart, is coupled to the rotary component, the two parts being coupledelastically for rotation together.

[0019] Preferably, control of disengagement of the clutch is carried outelectrically, the gearbox is a so-called automated gearbox, gear changesbeing controlled by a computer which takes into account, in particular,information delivered by a sensor as to the speed of the input shaft ofthe gearbox, and by a sensor as to the speed of the output shaft of thegearbox, firstly after the clutch is disengaged, and secondly after thedamper has been tuned to the speed of the input shaft of the gearbox,having regard to the new gear ratio to be engaged; a mechanical gearboxwith assisted control can of course also be used: the engine ensuresassistance to the synchronising operation, governed by a detector of thegear ratio engaged.

[0020] In a modified application of the invention, the damper is used asan electric motor and controlled in such a way as to supply anadditional driving torque on the output shaft, besides that which issupplied by the engine of the vehicle.

[0021] In another modified version, the damper is used as an energyrecuperator during braking; the clutch is disengaged during the energyrecuperation phase; the gear ratios are changed down.

[0022] In order that the invention shall be more clearly understood,some embodiments, which are shown in the attached drawings, will now bedescribed by way of purely illustrative and non-limiting example.

[0023] In these drawings:

[0024]FIG. 1 is a diagram illustrating the application of the inventionto a transmission for a motor vehicle;

[0025]FIG. 2 is a partial view in cross section showing another version;

[0026]FIG. 3 is a plan view showing part of the spring of the driveshaft damper in FIG. 2;

[0027]FIG. 4 is a scrap view in cross section showing another version ofthe damper spring;

[0028]FIG. 5 is a view in cross section of a further version of thedamper;

[0029]FIG. 6 is a partial view, in cross section, showing anotherversion of the damper shown in FIG. 5;

[0030]FIG. 7 is a partial view in transverse cross section showing thearrangement of the windings in the damper of FIG. 6;

[0031]FIG. 8 is a scrap side view showing another arrangement of thewindings;

[0032]FIG. 9 is a diagram of the same kind as that in FIG. 1, showing afurther application of the invention.

[0033] With reference to FIG. 1, this shows the application of theinvention to a transmission for a motor vehicle comprising, startingfrom the engine 10 of the vehicle, the drive shaft or crankshaft 11, theengine being coupled to a flywheel or reaction plate 12, and a clutchmechanism consisting of a cover plate 13 which supports a pressure plate14 and axially acting resilient means, in this example a diaphragm 15.

[0034] Axially disposed between the reaction plate 12 and pressure plate14, a friction disc 16 carries at its outer periphery friction linerswhich are adapted to be gripped axially between the said plates 12 and14, and a central hub 17 which is connected elastically, throughcircumferentially acting springs 18, to the peripheral portion carryingthe said liners.

[0035] The hub 17 of the friction disc 16 is mounted in rotation on aso-called output shaft 19.

[0036] Since these clutches are well known, they will not be describedany more here.

[0037] A drive shaft damper 20 is mounted on the output shaft 19.

[0038] The damper 20 consists of a mass 21 or rotor, which is mountedfor rotation about the output shaft 19, with which it is coupledelastically through an interposed spring 22.

[0039] In accordance with the invention, modulating means are providedfor matching the frequency of the damper 20 to the frequency ofvibrations transmitted through the drive shaft 11 via the damper disc16, and not filtered by the latter.

[0040] These modulating means are of the electromagnetic type, and inthis example they consist of magnets located at the periphery of therotor 21, with which inductive windings, carried by a stator, which isnot shown but which is indicated diagrammatically at 23, are arranged tocooperate electromagnetically.

[0041] The damper 20 is tuned to a frequency which is within the rangeof frequencies to be damped out; by passing through the inductivewindings 23 a current which is a function of the amplitude measured, forexample by a vibration sensor not shown, that is to say the amplitude ofthe vibration to be damped out, an oscillating torque is set up which isopposed to the said vibration.

[0042] A computer 24 receives the measurement in real time of thevibration that remains to be damped out, so as to set the current whichis to pass through the windings 23, operation being therefore, withadvantage, of the closed loop type.

[0043] Thanks to the invention, the electric power consumed by thefiltering device is only of the order of a hundred watts.

[0044] In the diagram of FIG. 1, the windings 23 are disposed radiallyin line with the magnets of the rotor 21.

[0045] In a modified version in FIG. 2, they are disposed axially inline with the magnets.

[0046] More precisely, with reference to FIG. 2, this shows a driveshaft damper 120 consisting of a rotor 121 and a stator 126.

[0047] The stator 126 carries the windings 123; a ring 128 with anL-shaped cross section is carried by the stator 126 and providescentring for the coils and fastening of the stator 126.

[0048] The rotor 121 comprises a disc 129 which is provided with a hub130 mounted for free rotation on the output shaft 119 through, here, aninterposed plain bearing 131; the disc 129 carries, on its surface thatfaces towards the windings 123, magnets 127; an annular hoop 132, whichis for example made of steel, or glass fibres, or some other material,secures the fastening of the magnets 127 against centrifugal force.

[0049] A spring 122 couples the rotor 121 and output shaft 119 togetherelastically in rotation.

[0050] This spring 122, which is best seen in FIG. 3, is in the form ofa disc which is cut out in such a way that it has an annular outer rim133 and an inner annular rim 134, which are joined together by arms 135that are generally radial in this example.

[0051] The annular inner rim 134 has at its inner periphery teeth 136which are adapted to cooperate with grooves 137, FIG. 2, of the shaft119 so as to couple the spring 122 and output shaft 119 together inrotation.

[0052] The annular outer rim 133 has apertures 138 which are adapted tocooperate with axial bosses 139, FIG. 2, which are formed in the disc129 for coupling the rotor 121 and spring 122 together in rotation.

[0053] In the present case, the damper 120 is associated with a clutchin which the liners of the friction disc 116 are coupled rigidly withthe hub 117, while the reaction plate 112B, associated with the pressureplate 114, constitutes the secondary part of a two-part flywheel 112,the primary part 112A of which is coupled directly to the rotatingmember 111, the primary part 112A and secondary part 112B both beingcoupled elastically to each other in rotation, in this example throughinterposed springs 118 extending generally radially.

[0054] In FIG. 4, the damper 120 is similar to that in FIG. 2, but herethe spring 122 consists of a plurality of helical springs 150 which bearon the radial edges, on one side, of windows which are formed in aradial disc 151 which is coupled in rotation with the shaft 119, and onthe other side, of windows formed in counter-plates 152 disposed oneither side of the plate 151 and mounted in rotation on the shaft 119and coupled in rotation to the yoke 129 which carries the magnets 127.

[0055] As has been seen in particular with respect to FIG. 2, the rotor121 of the damper 120 is mounted on the shaft 119 by means of its hub130, the spring 122 being disposed kinematically between the rotor 121and shaft 119.

[0056] The drive shaft damper 220 shown in FIG. 5 is mounted on the endof the primary shaft 219 of the gearbox, the secondary shaft of whichcan be seen at 120. In this example it is the spring 222 that supportsthe rotor 221 of the damper; for this purpose it has an annular innerrim 234 in the form of a hub, which is secured axially on the end of theshaft 219 by a nut 241 screwed on to the shaft 219, with a washer 242interposed; the outer ends of the arms 235 of the spring 222 are in meshwith axial returns of the disc 229, in the form of a yoke carrying themagnets 227, in line with which the windings 223 carried by the armature226 of the stator are placed, which armature 226 is itself carried bythe base portion of a cover plate 243; preferably, the armature 226 ismade in laminated form, by winding a metallic band around the axis ofthe shaft 219, or in the form of a plurality of sintered iron elements,whereby to minimise losses due to Foucault currents.

[0057]FIG. 6 shows a variant of the drive shaft damper 220 which islocated at the end of the primary shaft 219 of the gearbox. In thiscase, the axial order of the stator 226 and rotor 221 has been reversed,the rotor 221 being disposed on the outside; the rotor 221 is mounted inrotation on the shaft 219 and carries, directed outwards, a skirt 244which extends parallel to the axis of the shaft 219 and which is formedwith circumferential slots 245, and the springs 222 engage on one sideagainst one of the edges of these slots; on the other side, the springs222 which extend circumferentially bear on transverse returns 246 of asolid ring 247 which is mounted in rotation on the shaft 219.

[0058] In this example, the windings 223 are in the form of coils whichare not interleaved but, as can be seen in FIG. 7, are disposed in twosuperimposed rows.

[0059] In another version they are interleaved, with the edge of onecoil lying on the edge of the next as shown in FIG. 8: in thisconfiguration, the coils are slightly inclined with respect to atransverse plane at right angles to the axis of the shaft 219.

[0060] Thanks to the drive shaft damper according to the invention, itis also possible to synchronise the shafts concerned during gearchanges, especially where the gear changes may be carried out by meansof electrically controlled actuators, as is the case in so-calledautomated gearboxes.

[0061] In the diagram of FIG. 1, such a gearbox 50 can be seen disposedbetween the input shaft 19 and output shaft 51 for driving the drivetrain 52 of a motor vehicle.

[0062] Thus, when the shaft 19 is released following the declutchingoperation, the velocity of this shaft is rapidly reset according to thegear ratio to be engaged; such an arrangement has the advantage that itgives the drive shaft damper the function of a centralised synchroniser,and conventional synchronisers arranged in each gear ratio are omitted;in addition, synchronisation time is reduced, as is cost.

[0063] Operation is precise, and is facilitated by the presence of speedsensors 53, 54 upstream and downstream of the gearbox 50; by providingfor an electrically controlled declutching actuator 55, the computer 24,which incorporates the electronic power control, generates all thefunctions described above, also having regard to certain parameters 55of the engine, such as torque, speed, etc.

[0064] As to the damping function of the drive shaft damper, its closedloop operation described above may be replaced by operation inaccordance with a vibration map, as a function of various parameterspredetermining the values of torque to be given to the damper.

[0065] It will also be understood that the damper may be used as anenergy recuperator, or even as an alternator and synchronous motor; withreference to FIG. 9, this shows an embodiment in which the damper 20 ismounted on the primary shaft 19 of the gearbox, downstream of a clutch58; this primary shaft 19 in this example carries two pinions 60, 62associated with two pinions 61, 63 respectively which are carried by thesecondary or output shaft 51; a controlled dog-clutch 64 ensures thatthe said secondary shaft 51 will be driven either by the pinion 61 or bythe pinion 63.

[0066] Thanks to a fastening device 56, the battery 57 of the vehiclemay be charged for example during a braking operation; by action on thebrake pedal 59, after the accelerator has been released, the clutch 57is disengaged and the damper 20 operates as a generator which dischargesinto the battery 57; in order that the speed of rotation of thegenerator is sufficiently high, the gears are changed down bycontrolling the clutch 64.

1. A filtering device for filtering out vibrations transmitted by arotating power component (11, 111) adapted to drive in rotation anoutput shaft (19, 119, 219), which device comprises a drive shaft damper(20, 120, 220) tuned to a frequency which is substantially inside therange of frequencies to be damped out, characterised by the fact thatmodulating means of the electromagnetic type are provided for thepurpose of matching the frequency of the damper (20, 120, 220) to thefrequency of the vibrations transmitted by the rotating component (11,111).
 2. A filtering device according to claim 1, characterised by thefact that the damper (20, 120, 220) comprises a rotor (21, 121, 221)consisting of a mass which is mounted elastically on the output shaft(19, 119, 219) and associated with a stator (126, 226), the modulatingmeans comprising electromagnetic means (23, 123, 223-127, 227) carriedby the rotor (21, 121, 221) and the stator (126, 226).
 3. A filteringdevice according to claim 2, characterised by the fact that theelectromagnetic means comprise magnets (127, 227) defining a successionof poles carried by the rotor (21, 121, 221) and coils (23, 123, 223)carried by the stator (126, 226) and defining a succession of polesdisposed in line with the magnets (127, 227).
 4. A filtering deviceaccording to claim 3, characterised by the fact that the coils (123,223) are disposed axially in line with the magnets (127, 227).
 5. Afiltering device according to claim 3, characterised by the fact thatthe coils (23) are disposed radially in line with the magnets.
 6. Afiltering device according to one of claims 2 to 5, characterised by thefact that the rotor is in the form of a disc (21, 121, 221) or isfrustoconical or cylindrical.
 7. A filter device according to one ofclaims 3 to 6, characterised by the fact that the magnets (127, 227) areheld in position radially by a counter-centrifugal radial retaining hoop(132).
 8. A filtering device according to one of claims 1 to 7,characterised by the fact that it includes a vibration sensor adapted tomeasure the amplitude of the vibration to be damped out.
 9. A filteringdevice according to one of claims 3 to 5 taken together with claim 8,characterised by the fact that means are provided for supplying currentto the coils (23, 123, 223) of the electromagnetic means, the saidsupply being responsive to the result of the measurement of amplitudeperformed by the vibration sensor, whereby to create in the damper (20,120, 220) a torque equal and opposite to that created by the saidamplitude.
 10. A filtering device according to one of claims 1 to 9,characterised by the fact that it comprises a main vibration damperdisposed on the output shaft upstream of the damper.
 11. A transmissionfor a motor vehicle of the type comprising a drive shaft (11, 111),coupled to a rotary component consisting of the crankshaft of the engineof the motor vehicle, an output shaft (19, 119, 219) coupled to thedrive shaft releasably through a clutch, a gearbox (50), the said outputshaft (19, 119, 219) being the input shaft of the gearbox (50), afiltering device being provided for filtering out vibrations emitted,and therefore transmitted, by the rotary component, characterised by thefact that the filtering device is a filtering device in accordance withone of claims 1 to
 10. 12. A transmission according to claim 11,characterised by the fact that the clutch comprises a reaction plate(12, 112B), which is coupled directly or otherwise to the rotarycomponent, a pressure plate (14, 114) which is coupled in rotation tothe reaction plate (12, 112B) but displaceable axially with respectthereto, the two plate, namely the reaction plate (12, 112B) andpressure plate (14, 114), being adapted to clamp between them, under theaction of axially acting resilient means (15), friction liners carriedby a friction disc (16, 116) at its outer periphery, the said frictiondisc (16, 116) having a hub (17, 117) which is mounted in rotation onthe output shaft (19, 119, 219).
 13. A transmission according to claim12, characterised by the fact that the friction disc (16) comprises atorsion damper which constitutes the main damper.
 14. A transmissionaccording to claim 12, characterised by the fact that the reaction plate(112B) constitutes the secondary part of a two-part flywheel (112), theother part of which, namely the primary part (112A), is coupled to therotary component (111), the two parts (112A, 112B) being coupledelastically for rotation together (118).
 15. A transmission according toone of claims 11 to 14, characterised by the fact that control ofdisengagement of the clutch is carried out electrically, the gearbox(50) is a so-called automated gearbox, gear changes being controlled bya computer (24) which takes into account, in particular, informationdelivered by a sensor (53) as to the speed of the input shaft (19) ofthe gearbox (50), and by a sensor (54) as to the speed of the outputshaft (51) of the gearbox (50), firstly after the clutch is disengaged,and secondly after the damper (20) has been tuned to the speed of theinput shaft (19) of the gearbox (50), having regard to the new gearratio to be engaged.
 16. A transmission according to one of claims 11 to15, characterised by the fact that the damper (20, 120, 220) is used asan electric motor and controlled in such a way as to supply anadditional driving torque on the output shaft (19, 119, 219), besidesthat which is supplied by the engine (10) of the vehicle.
 17. Atransmission according to one of claims 11 to 15, characterised by thefact that the damper (20) is used as an energy recuperator duringbraking.
 18. A transmission according to claim 17, characterised by thefact that the clutch (58) is disengaged during the energy recuperationphase.
 19. A transmission according to claim 18, characterised by thefact that the gear ratios are changed down.